1. Field of the Invention
The present invention relates to an image forming apparatus provided with an anode section and a cathode section, and particularly to a flat panel display which emits lights via an electron beam.
2. Related Background Art
In recent years, a flat panel type image forming apparatus formed of an anode section and a cathode section has been broadly researched and developed. An electron emitting device for use is constituted, for example, of a field emitter, a surface conduction electron emitting device, and the like.
One example of use of the electron emitting device is proposed in U.S. Pat. No. 5,592,056, Japanese Patent Application Laid-Open Nos. 10-134740, 10-326583, and the like.
A schematic sectional view of such image forming apparatus is shown in FIG. 9. These image forming apparatuses are different in the structure of the electron emitting device, a driving method, and the like, but are characterized in common in that a cathode section 5 constituted of an electron source of a plurality of electron emitting devices is allowed to emit electrons, and that an anode section 4 is disposed in the vicinity of the cathode section 5. Additionally, numeral 1 denotes an anode substrate, 2 denotes an outer frame, 3 denotes a cathode substrate, and these components form a hermetically sealed container 7. A high vacuum of 10xe2x88x925 Pa or more is maintained in the hermetically sealed container. A phosphor is placed on this anode section 4, and is irradiated with electrons accelerated by a voltage applied to the anode electrode 4, so that the phosphor emits light and an image can be formed.
In the flat panel type image forming apparatus, a distance between the cathode section 5 and the anode section 4 is in a range of about several hundreds of micrometers to several millimeters.
Usually, when the image forming apparatus forms images for a long time, a vacuum arc discharge is observed in some cases. The current of this abnormal discharge differs with the voltage applied to the anode electrode included in the anode section, the region of the anode electrode, the distance between the anode section and the cathode section, and the like, but in some cases ranges from several amperes to several hundreds of amperes. The abnormal discharge is considered to be caused by an insufficient vacuum state between the cathode section and the anode section, or by an abnormal electric field formed by an electrode shape or a triple junction constituted of the contact point of the vacuum, electrode (metal) and insulating material.
Once such abnormal electric discharge occurs, the current is concentrated on the discharge section, and the anode and cathode sections are damaged in some cases. This vacuum arc discharge results in a large current, and a large amount of Joule heat by the current may cause the collapse of the electron emitting device in the cathode section. Moreover, the current concentration forms an unstable potential in the cathode section and connection wiring. As a result, the devices connected via the wiring are considered to be damaged. A conventional technique of providing the anode section with a resistor section to suppress the vacuum arc generation is disclosed, for example, in the Japanese Patent Application Laid-Open No. 10-134740.
According to one aspect of the present invention, there is provided an image forming apparatus comprising: a cathode substrate on which an electron emitting device is disposed; and an anode substrate provided with an anode electrode partially having a gap, and disposed opposite to the cathode substrate. The anode electrode is a physically continuous electrode comprising a plurality of conductive films electrically interconnected in series.
According to another aspect of the present invention, there is provided an image forming apparatus comprising: a cathode substrate on which an electron emitting device is disposed; and an anode substrate provided with an anode electrode partially having a gap, and disposed opposite to the cathode substrate. The anode electrode has an inductance of 1 xcexcH or more.
According to another aspect of the present invention, there is provided an image forming apparatus comprising: a cathode substrate on which an electron emitting device is disposed; and an anode substrate provided with an anode electrode, and disposed opposite to the cathode substrate. The anode electrode is an electrode formed by physically connecting a plurality of substantially rectangular conductive films, the plurality of conductive films are arranged substantially parallel with one anther in a longitudinal direction, and arranged with gaps in a direction substantially orthogonal to the longitudinal direction, and adjacent conductive films are interconnected at one end in the longitudinal direction so that the plurality of conductive films are electrically interconnected in series.
According to another aspect of the present invention, there is provided an image forming apparatus comprising: a cathode substrate on which an electron emitting device is disposed; and an anode substrate provided with an anode electrode, and disposed opposite to the cathode substrate. The anode electrode is a physically continuous electrode having a substantially square shape, a plurality of linear gaps (recessed portions) are extended from outer peripheral portions corresponding to two opposite sides among the sides of the square shape, the linear gaps (recessed portions) are substantially parallel with one another, the gap (recessed portion) extended from one of the two sides are extended toward the other side, and the linear gaps (recessed portions) are arranged in a zigzag pattern.
According to another aspect of the present invention, there is provided an image forming apparatus comprising: a cathode substrate on which an electron emitting device is disposed; and an anode substrate provided with an anode electrode partially having a gap, and disposed opposite to the cathode substrate. The gap has a spiral shape extended toward the central portion of the anode electrode from the outer peripheral portion of the anode electrode.
According to another aspect of the present invention, there is provided an image forming apparatus comprising: a cathode substrate on which an electron emitting device is disposed; and an anode substrate provided with a conductive film partially having a gap, and disposed opposite to the cathode substrate. The conductive film has a shape drawn with a single stroke.
According to another aspect of the present invention, there is provided an image forming apparatus comprising: a cathode substrate on which an electron emitting device is disposed; and an anode substrate provided with an anode electrode partially having a gap, and disposed opposite to the cathode substrate. The anode electrode comprises a physically continuous anode electrode having a substantially square shape, and has a spiral shape extended toward the central portion of the anode electrode from the outer peripheral portion of the square shape.